The Emirates witnessed a very disappointing afternoon when the Hornets were there to beat the Gunners 2-1 to dump the holders of the trophy out of the tournament.
This victory takes Watford to the next round and a step closer to the FA Cup, the only real chance of any success this season. But the Vicarage outfit have already exceeded expectations in their first season in the top flight.
Slavisa Jokanovic, the manager who bought the Hornets to the Premier League after a superb season in the Championship last campaign was replaced by ex-Real Madrid player Quique Sanchez Flores after he resigned from Getafe in February last year.
Since taking over the Premier League outfit at the start of this season in June, Flores has hardly put a foot wrong in the top flight.
He trusted an old school 4-4-2 formation and used the likes of Troy Deeney who has been a savior of the club over the years and Odion Ighalo who has just been sensational since he started playing in the Premier League.
He also has a strong mid-field that can dictate the game and has outplayed many of the top teams in the Premier League.
Watford had a slow start to the season but the victory over Liverpool in December followed by the draw at Stamford Bridge lifted the club’s confidence and what has followed has been nothing but great for the club.
They have looked comfortable against the weaker sides this season and have not dropped too many points from winning positions. They have learnt how to hold on to a lead and finish off games and have found themselves in the 14th place in the points table, with 37 points on the board with 10 games to go in the season.
This is more than just remarkable as Watford were just promoted into the top flight this season. The likes of Norwich City who were promoted along with the Hornets are facing a battle for relegation and this shows the amount of work that was carried on by Flores at the Vicarage Road.
With a place in top flight guaranteed for next season, there is nothing much to play for the club this season except for the FA Cup.
They had an easy run in the FA Cup until the Arsenal game where they beat struggling Newcastle, Nottingham Forrest and Leeds on their way to the quarter-final.
They were superb against Arsenal away from home where they dominated the game and put to work the game-plan of the manager in fine fashion helping the holders of the cup out of the competition.
They still have a number of big games in the Premier League including games against Arsenal, Everton and Liverpool but if they can continue their form and have a strong finish to the season, it will help them improve their squad before the end of next season.
Flores has already shown that he can attract top quality stars after the transfer of Mario Suarez in January and if he can convince the board to let him splash the cash in the summer, Watford are in with a real chance of a better season next campaign.
But until then, they will have to give their all in the FA Cup and with just Everton, United and West Ham left in the FA Cup, Watford have a great chance to run away with silverware in their first season in the top flight.
Do you think Watford can win the FA Cup this season?